Warranty is given as the time you buy the domain name, if you buy it for X years then the warranty will last for X years.
Is it possible to transfer the domain to the buyer's account? "easily renewed by you" but who knows where you will be after one or two years? I never recommend to anyone when buying a domain that he is not under his control.
.com registration on domains. google cost $12. Whether it is safe legal your registration method? here are already reselling domains using a stolen credit card for payments. I don't have to tell you that all domains have been taken away by the registrar.
Of course, I transfer the domain to the buyer's account, he has full ownership on the domain itself. Sold hundreds of domains so far and 100% satisfaction, before you judge and go against something you should check it. How can you give a negative feedback against something you never checked and not even fully understand how it works.
I wouldn't do it if it wouldn't be convenient and zero problems to the customers because I work with long term customers and that's my true income.
I can give you a vouch copy so you can see it by yourself.